Spring核心学习（3）为Bean注入属性

前导：开始学习Spring核心思想，通过一个山寨精简版Spring代码结合学习。

内容：1.Propertyvalue-保存属性注入信息。2.AutowireCapableBeanFactory-可自动装配的BeanFactory。

这里我们重新定义了BeanDefinition，增加了属性列表这个字段，我们将为bean附加额外的属性，所以我们又定了PropertyValues、PropertyValue来辅助，当我们为bean定义的时候同时设置他的属性，通过反射机制来动态的附加到bean里，来达到类似配置文件的效果。

BeanDefinition：

public class BeanDefinition {private Object bean;private Class beanClass;private String beanClassName;private PropertyValues propertyValues;public BeanDefinition() {}public Object getBean() {return bean;}public void setBean(Object bean) {this.bean = bean;}public Class getBeanClass() {return beanClass;}public void setBeanClass(Class beanClass) {this.beanClass = beanClass;}public String getBeanClassName() {return beanClassName;}public void setBeanClassName(String beanClassName) {this.beanClassName = beanClassName;try {this.beanClass = Class.forName(beanClassName);} catch (ClassNotFoundException e) {e.printStackTrace();} }public PropertyValues getPropertyValues() {return propertyValues;}public void setPropertyValues(PropertyValues propertyValues) {this.propertyValues = propertyValues;}}

PropertyValue：

/** * 用户bean的属性注入 * @author acer * */public class PropertyValue {private final String name;private final Object value;public PropertyValue(String name, Object value) {this.name = name;this.value = value;}public String getName() {return this.name;}public Object getValue() {return this.value;}}

PropertyValues：

/** * 包装一个对象所有的PropertyValue * @author acer * */public class PropertyValues {private final List<PropertyValue> propertyValueList = new ArrayList<PropertyValue>();public PropertyValues() {}public void addPropertyValue(PropertyValue pv) {//TODO:这里可以对于重复propertyName进行判断，直接用list没法做到this.propertyValueList.add(pv);}public List<PropertyValue> getPropertyValueList() {return propertyValueList;}}

BeanFactory：

public interface BeanFactory {Object getBean(String name);void registerBeanDefinition(String name, BeanDefinition beanDefinition) throws Exception;}

AbstractBeanFactory：

public abstract class AbstractBeanFactory implements BeanFactory{private Map<String, BeanDefinition> beanDefinitionMap = new ConcurrentHashMap<String, BeanDefinition>();@Overridepublic Object getBean(String name) {return beanDefinitionMap.get(name).getBean();}@Overridepublic void registerBeanDefinition(String name,BeanDefinition beanDefinition) throws Exception{Object bean = doCreateBean(beanDefinition);beanDefinition.setBean(bean);beanDefinitionMap.put(name, beanDefinition);}/**     * 初始化bean     * @param beanDefinition     * @return     */    protected abstract Object doCreateBean(BeanDefinition beanDefinition) throws Exception;}

AutowireCapableBeanFactory：

/** * 可自动装载内容的BeanFactory * @author acer * */public class AutowireCapableBeanFactory extends AbstractBeanFactory{@Overrideprotected Object doCreateBean(BeanDefinition beanDefinition) throws Exception{Object bean = createBeanInstance(beanDefinition);applyPropertyValues(bean, beanDefinition);return bean;}protected Object createBeanInstance(BeanDefinition beanDefinition) throws Exception {return beanDefinition.getBeanClass().newInstance();}protected void applyPropertyValues(Object bean, BeanDefinition mbd) throws Exception {for (PropertyValue propertyValue : mbd.getPropertyValues().getPropertyValueList()) {Field declaredField = bean.getClass().getDeclaredField(propertyValue.getName());declaredField.setAccessible(true);declaredField.set(bean, propertyValue.getValue());}}}

HelloWorldService：

public class HelloWorldService {    private String text;    public void helloWorld(){        System.out.println(text);    }    public void setText(String text) {        this.text = text;    }}

BeanFactoryTest：

public class BeanFactoryTest {@Testpublic void test() throws Exception{// 1.初始化beanFactoryBeanFactory beanFactory = new AutowireCapableBeanFactory();// 2.bean的定义BeanDefinition beanDefinition = new BeanDefinition();beanDefinition.setBeanClassName("step3.test.HelloWorldService");// 3.设置属性PropertyValues propertyValues = new PropertyValues();propertyValues.addPropertyValue(new PropertyValue("text", "Hello World! from step3!"));beanDefinition.setPropertyValues(propertyValues);// 4.生成beanbeanFactory.registerBeanDefinition("helloWorldService", beanDefinition);// 5.获取beanHelloWorldService helloWorldService = (HelloWorldService) beanFactory.getBean("helloWorldService");helloWorldService.helloWorld();}}